In U.S. Pat. No. 4,650,386, assigned to the assignee of the present invention, a commercially available articulable positioning anchoring device is described which is a fixed position toggle bolt, i.e., wherein the anchor device is manipulated and fixed into position prior to placement of a bolt and the object to be anchored. The disclosure of said patent is included herein by reference thereto. This prior art device comprises a metal anchoring element in the form of a U-shaped channel with a centrally located raised and threaded aperture for engagement with an inserted bolt. The metal anchoring element is manipulated into position against a non-directly accessible wall or substrate surface, by means of frangible legs made of a material such as polystyrene which are provided with a series of axially extending tooth-like protuberances. These teeth define the various selected points of breakage and provide a ratchet structure for operation as will be described.
A first end of each of the manipulating legs is provided with two opposite, laterally extending, small protrusions which are adapted to be rotatably fitted into apertures formed in the upright portion of the U-shaped metal anchoring element. The nut aperture is situated between the so-connected legs, whereby passage of a bolt is possible between the legs. With this connection between the legs and the U-shaped metal anchor element, the metal anchoring element is controllably swivelable relative to the legs, between a perpendicular or axial position to substantially coextensive with the legs. Thus, during use, an aperture sufficient in diameter to accommodate the small end of the metal anchoring element is made in the substrate, and the metal anchoring element is swiveled, by control of the legs into the coextensive position.
The other ends of the legs are formed into manipulating handle elements and, in the embodiment shown in said patent, the legs are connected to each other with a slidable connection whereby sliding one leg relative to the other causes the metal anchoring element to swivel, as described.
In use, the metal anchoring element is inserted into the aperture and when it clears the opposite side is caused to assume a perpendicular position by alignment of the manipulating handles of each of the legs. The anchoring element is then drawn into contact with the distal or blind side of the substrate by pulling of the handle elements in a direction away from the substrate. A sliding collar member, initially fitted onto each of the legs, adjacent the handle elements, is made to slide up the legs (i.e., pushed) to a position whereby the substrate is snugly sandwiched between the anchoring element and the collar. The portions of the legs between the collar and anchoring element, in conjunction with the connected collar and anchoring element, provide a locked structure which serves to maintain the anchor in position even without an inserted bolt. When the collar is positionally snugged, the residuals of the legs are broken off and discarded.
In order to maintain and lock the collar in the snugged position and to provide a variable position emplacement, the legs are provided with a continuous range of axially or laterally extending tooth like protrusions (i.e., beveled teeth which widen in thickness towards the anchoring element) and the collar is internally provided with a step engagement elements which ride over the teeth of both legs in a one way direction, in the manner of a ratchet engagement. Movement of the collar is accordingly locked in the one way direction and the collar cannot easily be backed down the leg. Breakage off of the excess portion of the legs is at a base of a tooth with the widened upper end of the tooth locking the collar in place.
Despite its utility and widespread popularity there are however several disadvantages with the anchor of the prior art. Firstly, the teeth, for effective operability, protrude with relatively sharp edges and for some users this may be irritating to the fingers upon breakage of the legs. Secondly, because of the need to maintain frangibility, the legs are perforce thin and, as a result, may, on standing or improper storage, tend to warp or become misshapen. The legs may also become somewhat elastic which thereby increases an effort required for the breakage thereof. Finally, movement of the collar along the beveled teeth is somewhat difficult with resistances being involved in the collar tooth riding up the bevel and past the step engagement element.